1. Field of the Invention
Apparatuses and methods consistent with the exemplary embodiments of the present invention relate to a monopole antenna having a matching function. More particularly, the exemplary embodiment of the present invention relates to a monopole antenna having a matching function, which facilitates impedance matching and reduces the antenna size.
2. Description of the Related Art
A general monopole antenna is fabricated with a length of
      λ    4    ,which is half the length of a dipole antenna, by an imaging effect using a ground. Thus, the monopole antenna is frequently used in small devices such as mobile communication terminals. Yet, in accordance with the miniaturization of small devices, there is a demand for further miniaturization of the monopole antenna.
To this end, the monopole antenna is formed like a patch antenna and the antenna is miniaturized by changing its shape. However, when the antenna is miniaturized, disadvantageously, the gain of the antenna is lowered and the bandwidth of the operating frequency shrinks. Also, it is difficult to match the impedance of the antenna to 50Ω.
To address these shortcomings, a matching circuit is separately provided to the small antennas for impedance matching. Although it is preferable to place the matching circuit adjacently to the antenna at most, the matching circuit may be positioned adjacently to the antenna or away from the antenna according to its design. When the matching circuit lies away from the antenna, a separate wire is required to interconnect the antenna with the matching circuit. The wire may cause reactance through the operation with the circuit board. The resulting reactance affects the matching circuit and thus changes the impedance of 50Ω which has been matched by the matching circuit.
Without the wire, after the matching circuit is mounted to the device, mismatching may occur because of the operation with another circuit element. When the mismatching occurs, the design of the matching circuit needs to be modified. Such a design change is cumbersome, and it is not easy to change the design of the matching circuit. In addition, a space for the separate matching circuit is required.
Therefore, a solution is needed to reduce a size of a device having a monopole antenna and to facilitate the design of the matching circuit by minimizing the space occupied by the matching circuit in the design phase of the monopole antenna.